Amp design.

[PENG]

EDIT: I think I'm wrong again...I take the peak value and divide it by 2^(10/3) right? If so, I get around 60W average to the entire speaker and 15% of that gives me 9W continuous to the example tweeter and probably a bit more to mine. I think I'm slowly answering my own questions about the article but if anybody can help clarify my understanding it will be much appreciated.

I think you may be right to assume your amp's 300W RMS can output 600W Peak for a sinusoidal waveform. In the ESP article, they assume a 10 to 20 dB ratio for music waveform, not sinuisoidal. Having read this article, I think I can now see why hifi can pump 900W into his line arrays without damaging them, if got his number from the Mc's wattmeter (peak). Drop that 900W peak by 10 dB you get 90W average power. I am really tempted to email Mc for an explanation.

 

[zumbo]

Bryston raised my curiosity. Had a look at the 5-channel 9B SST.

140W into 8ohms .005%
200W into 4ohms .007%
76 lbs

5k new. Found a demo for $2800 OBO with full warranty.

McIntosh MC 205

200W into 8ohms .005%
200W into 4ohms .005%
81 lbs

Dealer states he will sell for 5k +/-.

Looked at Krell Showcase Amp. Doesn't do it for me. Less weight(56lbs), and much more distortion(.20 @ 4ohm). Claims 125 @ 8ohm, 250 @ 4ohm. At 56lbs? 25lbs less than the McIntosh?

The demo deal on the Bryston looks good, as do the specs. But, what about when I replace my speakers in the future? If I go with 8ohm, the McIntosh will still provide the 200W @ 8ohm, while the Bryston drops down to a stated 140W @ 8ohm. To me, McIntosh still has the edge in my situation, and would seem to have the edge in any other similar situation. Also, resale value. It's a 200W amp any way you slice it.

 

[highfihoney]

I understand you point but 900W continuous should still fry a speaker that is rated for 250W max. There is no way out to this.

There may be another explanation, if that 900W continuous you referred to was read off the MC1201's wattmeter, then depend on the position selected, it may be reading either the instantaneous peaks when in the watts position or the peaks of a sequence of peaks if in the hold position. In either case, that meter does not seem (not 100% sure) to be for indicating rms watts. For a pure sine wave, V or I pk=sqrt2*V, or Irms so peak power will be 2 times rms power. Music waveforms are not sinusoidal so the 2 to 1 ratio may not hold true and is likely higher. So the true rms power into you speakers may be nowhere near the 900W indicated on the 1201's wattmeter. I am thinking of emailing McIntosh and ask them to clarify a little more how those wattcmeters work and what exactly do they indicate.

As a sidebar, I know you did not say that in you post but others had in the past, about the inverse square rule for SPL vs distance. That rule is only true for open field condition. In a room it depends on the acoustic environment. In my listening environment, whether I place my meter at 6 ft away or 16 ft away, the SPL level does not change much, in some position it actually goes up slightly with distance.

Hi peng,i only made known the distance at which i measured because my bass cabinets are placed in corners right now & i can gain about 2 db on the meter at 3 ft due to bass cabinet placement.

The readings i get on the watt meters on the mac amps are an accurate representation of actual watts going to the speakers,there are different settings the meters can be placed in but meter placement isnt an issue,the meters dont bounce around like most analog meters & it is very easy to see where the peaks are as oposed to running wattage or rms,voltage & current are taken into consideration & the result is what we see on the meter,its not a bouncy type meter & the readings are very smooth.

In the hold position the meters slow down drasticaly to show the peak output but you can still see meter movement between the lowest peak & highest peak up to 4,800 watts in this position,these readings are far different than in the watt mode used to measure output,when switched from "watt" to "hold" the meter will slow at the lowest peak & go to the highest peak,when switched back to the watt setting the meters will drop to show running wattage or rms.

About 2 years back i briefly spoke with Chuck Hinton at mac labs about an issue i was having with my mc2102 tube amps meters & we touched base on this subject,my understanding of serious tech talk is small so i was taking in as much as i could & my understanding was that the meters show accurate rms,im sure either Chuck or Ron over at mac labs could give an in depth explaination.

From the Mcintosh website.

The output watt meters respond to 95% of full scale in a single cycle tone burst at 2khz. Voltage & current output are electronicly measured,multiplied & fed to a special circuit that accelerates the pointer movement in the upward direction. When the pointer reache's it's peak it pauses only long enough for the human eye to perceive its position,then drops. It is allmost 10 times faster than a professional VU meter.

 

[PENG]

The readings i get on the watt meters on the mac amps are an accurate representation of actual watts going to the speakers,there are different settings the meters can be placed in but meter placement isnt an issue,the meters dont bounce around like most analog meters & it is very easy to see where the peaks are as oposed to running wattage or rms,voltage & current are taken into consideration & the result is what we see on the meter,its not a bouncy type meter & the readings are very smooth.

In the hold position the meters slow down drasticaly to show the peak output but you can still see meter movement between the lowest peak & highest peak up to 4,800 watts in this position,these readings are far different than in the watt mode used to measure output,when switched from "watt" to "hold" the meter will slow at the lowest peak & go to the highest peak,when switched back to the watt setting the meters will drop to show running wattage or rms.

About 2 years back i briefly spoke with Chuck Hinton at mac labs about an issue i was having with my mc2102 tube amps meters & we touched base on this subject,my understanding of serious tech talk is small so i was taking in as much as i could & my understanding was that the meters show accurate rms,im sure either Chuck or Ron over at mac labs could give an in depth explaination.

From the Mcintosh website.

The output watt meters respond to 95% of full scale in a single cycle tone burst at 2khz. Voltage & current output are electronicly measured,multiplied & fed to a special circuit that accelerates the pointer movement in the upward direction. When the pointer reache's it's peak it pauses only long enough for the human eye to perceive its position,then drops. It is allmost 10 times faster than a professional VU meter.

Thank you for responding. I browsed their site and I found every indication that those meters read peak power not average power. This is one of such indication:

http://www.mcintoshlabs.com/data/brochures/MC2051.16.07.pdf

I am not talking about the peak as to the maximum of the rms value, but peak of the waveform itself. The thing is, for music waveforms, the ratio of peak to rms could be quite high. The ESP article cited a 10 to 20 dB. As I said, I'll probably email them.

 

[highfihoney]

The thing is, for music waveforms, the ratio of peak to rms could be quite high. The ESP article cited a 10 to 20 dB. As I said, I'll probably email them.

Im confused at this point,i would be happy if you emailed mac to clear this one up,on Roger Russell's site he very briefly touches base on the meters & talks a bit about wave form but from the way he wrote everything the summary of the meters was left open to reader interpretation weather they used the wave form or abandoned measuring the wave form because it was at too fast a cycle.He also leave's the summary with a statement saying more changes were planned for the metering systems used.

Hmmmmm.

 

[highfihoney]

I'll probably email them.

Hi peng,i went ahead & emailed roger russell & asked him these questions,ive spoke with him before & he always responds within a day or two,if he is ok with me posting a copy of his response i will do so,hopefully one of us can get real info.

 

[mtrycrafts]

It doesn't try to double. How did you miss that point. If your statement were true, McIntosh would be the laughing stock of the audio world, and they certainly wouldn't be held in such high regard.
From the McIntosh site:
Unlike other high-current designs, The MC205 delivers the same 200 watts per channel into both 4-ohm and 8-ohm loudspeakers. The Dynamic Power Manager automatically controls and optimizes the power supply’s voltage and current balance delivering higher voltage that 8 ohm speakers require, and automatically adjusting for current-hungry 4 ohm speakers.
Power Guard
Power guard is another patented McIntosh innovation. When an amplifier is overdriven, by a sudden music peak, for instance, it can "clip" and send a burst of damaging energy to your speakers. This is the most common cause of damage to the "tweeter" element of speakers. Power Guard, on optical-electronic circuit, prevents clipping by instinctively turning the volume down, and then back up, in as little as 1/1000 of a second. Hard clipping is avoided, and speakers are safe while ensuring maximum safe power output.

I didn't miss anything. I made that point knowing it will not double up on power knowing it will maintain the same. But, if the need is there, what then? Will it shut down? Will it clip? What will it do when the requirement is there but the amp cannot meet that requirement? It must, or else suffer the consequences.
Turning the volume down is not an option!!! Then, it becomes a poor design that can only output half the needed demand.
But, that is what the specs say. Unable to increase power as you decrease the load impedance.
That should not be an issue, but it is not a special amp compared to others that can increase power when impedance decreases, even if they do not double up on power and it performs better.

There is a Yam power amp, that can do better, rated better as to power, all the way down to 1 or 2 ohms, increasing power as load impedance decreases. Not very expensive but not as sexy as the Mc.

 

[Yamahaluver]

http://www.yamaha10000.com/mx10000.htm

How about this amp? 1200W at 1ohm, S/N ratio of 132dB, 250W at 8ohms with 0.001%THD, 400W at 4ohms, 0.002%THD, weighs in at over 100lb. Dual 1200VAx2 power transformers.

 

[zumbo]

I am looking at a 5-channel amp, not a two channel. A current model available in the US would help as well. There are many 2-channel amps with better specs than 5-channel. Yet to see one that compares.

Yamaha MX-10000: Info taken from the link provided.
Price: 800,000 Yen

In keeping with its cost-no-object design, construction and performance, Yamaha gave a list price--in 1987--of 800,000 yen! In today's U.S. dollars, it would cost $6,977.00. Using an online inflation calculator using the closest year available (2005), this amplifier roughly had a list price in the United States in 1987 of $4150.00. A price check in the 1987 or 1988 Audio Magazine Buyer's Guide will be forthcoming. Audiophiles may never again see this kind of quality and power from Yamaha again--unless, of course, the company comes out with the Second Centennial Edition!

 

[zumbo]

I didn't miss anything. I made that point knowing it will not double up on power knowing it will maintain the same. But, if the need is there, what then?

Controls the need, while keeping the distortion, and heat in check.

Will it shut down?

No

Will it clip?

NO

What will it do when the requirement is there but the amp cannot meet that requirement?

Control the output to keep from overdriving my little 6.5" speakers.

It must, or else suffer the consequences.

It's the speaker that will not suffer.

Turning the volume down is not an option!!! Then, it becomes a poor design that can only output half the needed demand.

The "Power Guard" feature is in most McIntosh amps, if not all. Again, if your statement were true, they would be the laughing stock of audio.

But, that is what the specs say. Unable to increase power as you decrease the load impedance.

It is a design. It is able. Just not designed that way. Do you honestly think McIntosh can't design an amp to double it's power?

That should not be an issue, but it is not a special amp compared to others that can increase power when impedance decreases, even if they do not double up on power and it performs better.

It is an issue. Amps that keep their distortion down while producing the power needed for the application looks to be the idea. Looks to me like most, if not all, McIntosh solid state amps are designed in a similar way to produce their rated output under any ohm load.
Other brands in car audio do this as well. I believed this type of design was superior back in my car audio days. The price of car audio amps that could do this were the highest. They are the only amps that hold their value in car audio. I didn't know about McIntosh until later in life. It seems they are the superior product. They keep their composure,and they hold their value. This can't be a misconception of the audio world.

There is a Yam power amp, that can do better, rated better as to power, all the way down to 1 or 2 ohms, increasing power as load impedance decreases. Not very expensive but not as sexy as the Mc.

Only 2-channel. I doubt they can compete. Seriously. That's all you have? Yamaha? Not even close.

 

[MichaelJHuman]

...the power up to a constant 800 watts with peaks hitting over 1,000 watts...pushed a bit further to 925 watts with peaks comming close to 1,200 watts

Are you running all this off a single 15A circuit? I believe the max draw from a 15A circuit must be be less than 1800 Watts total.

 

[Yamahaluver]

My Yamaha amp can push 600W at 1ohms and runs happily at that impedance as mtrycrafts mentioned, also you can check the specs on the 10,000, the newer MX-D1 makes 500Wx2rms into 4/8ohms but yes they are all 2 channels, as 2 channel amps go, Yamaha's TOTL can compete with anything and everything out there, snob appeal aside.

Sterephille's review on MX-D1 at http://www.stereophile.com/solidpoweramps/405yamaha/index.html

 

[zumbo]

My Yamaha amp can push 600W at 1ohms and runs happily at that impedance as mtrycrafts mentioned, also you can check the specs on the 10,000, the newer MX-D1 makes 500Wx2rms into 4/8ohms but yes they are all 2 channels, as 2 channel amps go, Yamaha's TOTL can compete with anything and everything out there, snob appeal aside.

Sterephille's review on MX-D1 at http://www.stereophile.com/solidpoweramps/405yamaha/index.html

Looks like they can compete.(EDIT BELOW) But, I want a 5-channel amp. Here is something from your link for you and mtrycrafts. According to him, this thing is a POS.

Yamaha's Active Power Control System is claimed to allow the MX-D1 to vary its output with the speaker load (2–8 ohms) by detecting the output current and adjusting the power-supply voltage output limit. The result is said to be optimal power output regardless of speaker load. Dual, independent, switching-type power supplies operate at 88kHz and feature high-efficiency, low-noise, magnetic-coupling rectification circuits. Protection is provided by a "super-fast" circuit capable of measuring the current of a single pulse, as well as by a circuit that detects DC; each of these can instantly shut down the MX-D1 when necessary.

"Shut down". I don't want my amp to "shut down".

EDIT: I read the review. Didn't see anything that said this amp was worth it's price. I read some negatives. Enough to make me believe this amp couldn't compete with "snob brands".

 

[Seth=L]

"Shut down". I don't want my amp to "shut down".

Would you rather it set on fire?

I would rather have a Rotel, they have decent digital switching amplifiers.

 

[zumbo]

Would you rather it set on fire?

If it sounds like Stereophool described, "the bass focus was not all it should have been, which meant that image solidity suffered, and sometimes the bass became a bit woolly and just too big" , I might set it on fire myself.

 

[Seth=L]

If it sounds like Stereophool described, "the bass focus was not all it should have been, which meant that image solidity suffered, and sometimes the bass became a bit woolly and just too big" , I might set it on fire myself.

It is a digital switching amp, what do you expect from an unperfected amplifier topology?

 

[MichaelJHuman]

I thought switching amps were nothing new. Perhaps the use of faster switching circuitry is new though. I still don't see where digital comes from, but that always turns into a pointless debate when I bring it up.

I would love to ABX test one of those digital amps against any of my receivers at home. I suspect I could not hear the difference.

 

[mtrycrafts]

http://www.yamaha10000.com/mx10000.htm

How about this amp? 1200W at 1ohm, S/N ratio of 132dB, 250W at 8ohms with 0.001%THD, 400W at 4ohms, 0.002%THD, weighs in at over 100lb. Dual 1200VAx2 power transformers.

Are you selling? My boombox need an external amp

 

[Nuglets]

I didn't miss anything. I made that point knowing it will not double up on power knowing it will maintain the same. But, if the need is there, what then? Will it shut down? Will it clip? What will it do when the requirement is there but the amp cannot meet that requirement? It must, or else suffer the consequences.
Turning the volume down is not an option!!! Then, it becomes a poor design that can only output half the needed demand.
But, that is what the specs say. Unable to increase power as you decrease the load impedance.
That should not be an issue, but it is not a special amp compared to others that can increase power when impedance decreases, even if they do not double up on power and it performs better.

Like I said earlier in the post I think we all may be misunderstanding what it means when they say that it doesn't double down. I could be completely wrong and would like to know if I am, but here it goes. I am thinking that the Mac will do exactly as any other amp would do when the impedance drops but the thing it will not do is go above a maximum value in order to keep the heat and distortion at a lower level to help protect the equipment by not allowing you to overdrive the amp. For example if you have a 300W amp and you are using it well below it's maximum it will function like any other amp but as you reach 300W you may start running into the problems you describe. To avoid running into those problems you have to get an amp that matches your system and listening preferences. If you are planning on driving the amp to 300W on a regular basis and the impedance dips down while the amp won't allow it to exceed 300W you probably would get a bigger amp and the problem would be solved. Like I said I could be wrong but that's one way I can think of to logically describe the Mac design without knowing many details about it.

 

[highfihoney]

Are you running all this off a single 15A circuit? I believe the max draw from a 15A circuit must be be less than 1800 Watts total.

Hi michael,good question

Im running 2 20 amp circuits & a single 15 amp circuit,each monoblock has its own 20 amp line & the 15 amp circuit is for the preamp,cd player ect.